84 
COLOUR IN NATURE 
CHAP. 
variation. Most frequently it is a dark brown colour 
with white extremities ; sometimes the whole surface, 
including the polypes, is a vivid grass-green. Mr. 
Saville Kent describes a large colony which when 
first examined was pinkish-brown with greenish- 
white growing apices, the polypes throughout being 
a light emerald - green. On revisiting the colony 
after two years, it was found that the surface of the 
colony was of a clear seal-brown with white or pale 
lilac-blue tips, while the polypes were a clear red- 
brown, the tips of the tentacles only being a greenish- 
white. This variation is exceedingly marked, but 
the author seems to intimate that it was accompanied 
by a retardation of the growth of the colony. It is 
unnecessary here to give further details as to the 
colouring of the Madrepores ; the above descriptions, 
which are taken almost verbatim from The Great 
Barrier Reef are sufficient to prove the statement 
that these corals are remarkable for their contrast of 
colour, the contrast being produced by the respective 
colours of polypes and ground-substance, or by the 
different tints of mature and growing regions. The 
colours mentioned are exceedingly common through¬ 
out the genus. 
The same brilliancy of tint is observable among 
the other corals ; the banding of the surface of 
individuals is especially remarkable among the large 
sea-anemones or the solitary corals. The occurrence 
of bands of colour, especially round the tentacles, is 
admirably shown in many of our native sea-anemones, 
as are also the essential peculiarities of colouring. 
Note, for example, the green and magenta colouring 
of Anthea cereus , the bright turquoise beads at the 
